Perfluorocyclohexadiene



Patented Dec. 23, 1947 PERFLUOROCYCLOHEXADIENE Waldo B. Ligett, Detroit. Mich., and Earl T. Mc-

Bee, La Fayette, and Vincent V. Lindgren, West Lafayette, Ind., assignors to Purdue Research Foundation, West Lafayette, Ind., a corporation oi Indiana No Drawing. Application November 13, 1945,

. Serial No. 628,377

1 Claim.

This invention is concerned with a novel fluorocarbon, perfluorocyclohexadiene.

The compound is a non-flammable liquid, boiling at about 57- degrees centigrade .at atmos- 60 degrees centigrade with stirring. During three hours, 500 grams (2.3 moles) of antimony penta- 2 fluoride was added drop-wise thereto. The reaction mixture was heated to 120. degrees centigrade and maintained at this temperature for a period of about eight hours, during which time pheric pressure, having particular utility as an I bromine and part of the solvent were evolved intermediate to be used in the preparation of from the reaction mixture. The products or the compounds for the synthesis of fluorinated resins reaction were then washed with hot concentrated and additional utility as an intermediate in the hydrochloric acid to remove antimony salts.

preparation of hexafluorobenzene. AIter removal of the solvent, the solid product We have prepared the above named compound was dissolved in 500 milliliters of absolute ethanol. and have determined several of its physical con- This solution was added over a six hour period stants whereby it may be identified. Its preparato a refluxing suspension of 500 grams of zinc tion may be accomplished in a number of ways, dust in ethanol. By elevation of the temperature, one of which involves the reaction f bromine the more volatile products were distilled from the trifiuoride with an appropriate halogenated cyclic mixt e with m al ohoi- The hi her boil n compound, e. g., hexachlorobenzene. Bromine constituents were removed by steam distillation. trifluoride adds fluorine to any points of unsat- T e pr cts w re collected and alcohol was exuration and replaces, with fluorine, hydrogen and ed th e by Washing with Water! T part of the chlorine in the molecule. Any bromine Organic pro w rectified n a 100-Plate introduced is replaced by means of antimony go bielniak 0011mm and yielded perfill y pentafluoride. The product resulting from the diene, having the following structural formula: reaction with antimony pentafluoride is subse- F quently dehalogenated with zinc dust. resulting in the formation of perfluorocyclohexadiene. m0

The following example illustrates one method F F for the preparation of this new compound and is a in no way to be construed as limiting the inveng 7 tion thereto.

Five hundred and fift i ht grams of bromine Perfluorocyclohexadiene bolls at 56.0-57.0 detrmuorlde was placed in a nickel tube 5.2 cam grees centigrade at '743.mill1meters of mercury timeters in diameter and 50 centimeters in length, pressure absolute and has a refractive index of closed at one end and cooled to zero degrees Gem 1.3149 at 20 degrees centigrade, a density of 1.601 tigrade. Hexachlorobenzene was added thereto grams per milliliter at 25 fiegrees Centigrade and at a rate of about 100 grams per hour with confreezing pmm ,appmxlmately 6 *i cenu tmuous stirring by means or a motor driven grade. The experimentally determined molecumckel o inserted through the top of the tube lar weight was 223.0 compared with the theoretiand fitted with four blades. two inches apart on molecular weight of x the'rod. After each 100 gram quantity of hexawe claim: chlorobenzene had been added, the tube A perfluorocyclohexadiene having the iollowing heated to 85 degrees centigrade. maintained at 4 structural formula: this temperature for at least fifteen minutes and c then cooled to zero degrees centigrade. This pre- F vented the accumulation and possible subsequent '5 explosion or pyrolysis of unreacted starting ma- Fl F terials. A total or 400 grams of hexachloroben- 0 zone was charged to the reactor; the final ratio F being approximately three moles of bromine tri- WALDO B. LIGE'IT. fluoride to one mole of hexachlorobenzene. The EARL T. McBEE. entire reaction mixture was heated at 100 degrees VINCENT V. LINDGREN. centigrade for four hours, after which excess bromine trifluoride was destroyed by the addition REFERENCES CITED of cracked ice, v The following references are'oi record in the A liquid fluorochloro compound was used to disfile Of i P n solve the solid product which resulted and the Barral, "Bull." Soc. Chim. de France," third resulting solution was heated in a Pyrex flask to Series, VOL Pp 418-423 (1895)- Van der Linden, Reoueil des Trav. Chim. des Pays-Has, vol. 55, pp. 421-430 (1936). 

